Maplewood Mall is an aging shopping facility in the Twin Cities metropolitan area with 35 acres of impervious parking and road surfaces. Working with the Ramsey-Washington Metro Watershed District, the City of Maplewood, Ramsey County, and mall owner Simon Property Group, Barr designed a stormwater management system that reduces polluted runoff, while meeting regulatory, technical, and aesthetic challenges.
Incorporating an array of BMPs, the system significantly reduces stormwater runoff pollution while adding visual appeal and educational features. Along with rain gardens, porous-paver crosswalks, a sand filter, and a cistern that captures mall roof runoff for reuse as irrigation, the system features more than a mile of rock trenches planted with 200 trees. Engineered soils and subsurface irrigation allow plantings to thrive in the challenging parking lot conditions. The large-scale retrofit captures and treats 90 percent of the lot’s stormwater runoff. By intercepting, filtering, and/or infiltrating the first inch of runoff, the system removes over 60 percent of the phosphorus from the site that would otherwise flow into a nearby impaired lake. Barr added public art and educational components that explain to mall visitors the need for and the benefits of treating stormwater.
